The melting behavior of Nylon-6

6 ( PA6.6) and its blend with polyethersulfone (PES) were studied by differential scanning calorimetry. The Avrami equation was used to analyse the kinetics of isothermal crystallization of the samples. It was showed that crystallization temperature of the blend increased 15℃ than that of pure PA6

6 and the Avrami exponent of the sample containing 20% PES was 2.1 while 1.4 for pure PA6

6 The activation energies were 739.6 KJ/mol and 646.1 KJ/mol for the PA6.6 and the blend witj 20% PES

respectively. It was attributed to the nucleation of the PES during the crystallization of PA6.6.